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Specifications, Lock-in amplifiers – Atec Signal-Recovery-7280 User Manual

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Specifications

General
Dual-phase DSP lock-in amplifier operating
over a reference frequency range of 0.5 Hz to
2.0 MHz. Direct digital demodulation using a
main ADC sampling rate of 7.5 MHz.

Wide range of extended measuring modes and
auxiliary inputs and outputs. User-upgradeable
firmware.

Measurement Modes
The instrument can simultaneously show any
four of these outputs on the front panel display:

X

In-phase

Y

Quadrature

R

Magnitude

θ

Phase Angle

Noise

Harmonic

nF, n

≤ 32

Dual Harmonic

Simultaneously measures the signal at
two different harmonics F

1

and F

2

of the

reference frequency

Dual Reference

Simultaneously measures the signal
at two different reference frequencies,
F

1

and F

2

where F

1

is the external and F

2

the internal reference

Frequency Ranges for Dual Harmonic and Dual
Reference Modes:

Standard Unit

F

1

and F

2

≤ 20 kHz

With option -/99

F

1

and F

2

≤ 800 kHz

With option -/98

F

1

and F

2

≤ 2.0 MHz

Virtual Reference

Locks to and detects a signal without a
reference (100 Hz

≤ F ≤ 2.0 MHz)

Noise

Measures noise in a given bandwidth
centered at the reference frequency F

Spectral Display

Gives a visual indication of the spectral
power distribution of the input signal in a
user-selected frequency range lying
between 1 Hz and 2.0 MHz. Note that
although the display is calibrated in terms
of frequency, it is not calibrated for
amplitude. Hence it is only intended to
assist in choosing the optimum reference
frequency

Display

320

× 240 pixel (¼ VGA)

electroluminescent panel giving digital,
analog bar-graph and graphical indication
of measured signals. Menu system with
dynamic key function allocation. On-
screen context sensitive help

Signal Channel
Voltage Input
Modes

A only, -B only or
Differential (A-B)

Full-scale Sensitivity
0.5 Hz

≤ F ≤ 250 kHz

10 nV to 1 V in a
1-2-5 sequence

250 kHz

< F ≤ 2.0 MHz 100 nV to 1 V in a

1-2-5 sequence

Max. Dynamic Reserve > 100 dB
Impedance

100 M

Ω // 25 pF

Maximum Safe Input

20 V pk-pk

Lock-in Amplifiers

Voltage Noise

5 nV/

√Hz @ 1 kHz

C.M.R.R.

> 100 dB @ 1 kHz

Frequency Response

0.5 Hz to 2.0 MHz

Gain Accuracy

±0.3% typ, ±0.6%
max. (full bandwidth)

Distortion

-90 dB THD (60 dB
AC gain, 1 kHz)

Line Filter

attenuates 50, 60,
100, 120 Hz

Grounding

BNC shields can be
grounded or floated
via 1 k

Ω to ground

Current Input
Mode

Low Noise, Normal or
Wide Bandwidth

Full-scale Sensitivity

Low Noise

10 fA to 10 nA in a
1-2-5 sequence

Normal

10 fA to 1 µA in a
1-2-5 sequence

Wide Bandwidth
F

≤ 250 kHz

1 pA to 100 µA in a
1-2-5 sequence

F > 250 kHz

10 pA to 100 µA in a
1-2-5 sequence

Max. Dynamic Reserve > 100 dB
Frequency Response (-3 dB)

Low Noise

≥ 500 Hz

Normal

≥ 50 kHz

Wide Bandwidth

≥ 1 MHz

Impedance

Low Noise

< 2.5 k

Ω @ 100 Hz

Normal

< 250

Ω @ 1 kHz

Wide Bandwidth

< 25

Ω @ 10 kHz

Noise

Low Noise

13 fA/

√Hz @ 500 Hz

Normal

130 fA/

√Hz @ 1 kHz

Wide Bandwidth

1.3 pA/

√Hz @ 1 kHz

Gain Accuracy

± 0.6% typ, midband

Line Filter

attenuates 50, 60,
100, 120 Hz

Grounding

BNC shield can be
grounded or floated
via 1 k

Ω to ground

Reference Channel
TTL Input (rear panel)

Frequency Range

0.5 Hz to 2.0 MHz

Analog Input (front panel)

Impedance

1 M

Ω // 30 pF

Sinusoidal Input
Level

1.0 V rms*

Frequency Range 0.5 Hz to 2.0 MHz
Squarewave Input
Level

250 mV rms*

Frequency Range

2 Hz to 2 MHz

*Note: Lower levels can be used with the
analog input at the expense of increased
phase errors

Phase Set Resolution

0.001

° increments

Phase Noise at 100 ms TC, 12 dB/octave slope

Internal Reference

< 0.0001

° rms

External Reference < 0.01

° rms @ 1 kHz

Orthogonality

90

° ±0.0001°

Acquisition Time

Internal Reference

instantaneous
acquisition

External Reference 2 cycles + 50 ms

Reference Frequency Meter Resolution

1 ppm or 1 mHz,
whichever is the
greater

Demodulator and Output Processing
Output Zero Stability

Digital Outputs

No zero drift on all
settings

Displays

No zero drift on all
settings

Analog Outputs

< 5 ppm/

°C

Harmonic Rejection

-90 dB

Output Filters
X, Y and R outputs only

Time Constant

1 µs to 1 ms in a 1-2-5
sequence, and 4 ms

Slope (roll-off)

6 and 12 dB/octave

All outputs

Time Constant

5 ms to 100 ks in a
1-2-5 sequence

Slope

6, 12, 18 and 24 dB/
octave

Synchronous Filter

Available for
F < 20 Hz

Offset

Auto and Manual on X
and/or Y: ±300% full-
scale

Absolute Phase Measurement Accuracy

≤ 0.01°

Oscillator
Frequency

Range

0.5 Hz to 2.0 MHz

Setting Resolution

1 mHz

Absolute Accuracy ± 50 ppm

Distortion (THD)

-80 dB @ 1 kHz and
100 mV rms

Amplitude (rms)

Range

1 mV to 1 V

Setting Resolution

1 mV

Accuracy

±0.2%

Stability

50 ppm/

°C

Output Impedance

50

Sweep
Amplitude Sweep

Output Range

0.000 to 1.000 V rms

Law

Linear

Step Rate

20 Hz maximum
(50 ms/step)

Frequency Sweep

Output Range

0.5 Hz to 2.0 MHz

Law

Linear or Logarithmic

Step Rate

20 Hz maximum
(50 ms/step)

Auxiliary Inputs
ADC 1, 2, 3 and 4

Maximum Input

±10 V

Resolution

1 mV

Accuracy

±20 mV

Input Impedance

1 M

Ω // 30 pF

Sample Rate
ADC 1 only

40 kHz max.

ADC 1 and 2

17.8 kHz max.

Trigger Mode

Internal, External or
burst

Trigger Input

TTL compatible